Color formation is often carried out in the photographic emulsion layers or other layers in silver halide photographic materials in order to absorb light in a specific wavelength range.
Colored layers known as filter layers provided remote from the support are provided to control the spectral composition of the light incident upon the photographic emulsion layers, and colored layers known as antihalation layers are provided between the photographic emulsion layers and the support or on the surface opposite the photographic emulsion layers of the support in order to prevent the image fading, i.e., halation, caused by the scattering of light after passage or transmittance through the photographic emulsion layers and by incidence upon the photographic emulsion layers for a second time after reflection by interfaces or surfaces. With multilayer color sensitive materials, antihalation layers are placed between every layer.
Photographic emulsion layers are also colored to prevent a deterioration in image sharpness caused by the scattering of light in the photographic emulsion layers (this phenomenon is generally known as irradiation).
There are many cases in which the layers to be colored are formed from hydrophilic colloids, and water-soluble dyes are therefore usually included in the layers in order to color them. These dyes must satisfy the following conditions:
1. They must have an appropriate spectral absorption suited to the intended use. PA1 2. They must be photochemically inactive. In other words, chemically speaking, they must not impart any adverse effects, such as a reduction in speed, latent image fading or fogging, on the properties of the silver halide photographic emulsion layer. PA1 3. They must be decolored or removed by dissolution during photographic processing and must not leave any detrimental coloration on the photosensitive materials after processing.
There have been many efforts by those in the industry to discover dyes which satisfy these conditions and the dyes given below are known. Examples include oxonol dyes having pyrazolone nuclei or barbituric acid nuclei as disclosed in, for example, G.B. Patents 506,385, 1,177,429, 1,311,884, 1,338,799, 1,385,371, 1,467,214, 1,433,102 and 1,553,516, JP-A-48-85130, JP-A-49-114420, JP-A-55-161233, JP-A-59-111640 and JP-A-62-273527 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application") and in U.S. Pat. Nos. 3,247,127, 3,469,985 and 4,078,933, and the oxonol dyes having hydroxypyridone nuclei as disclosed, for example, in G.B. Patents 1,278,621, 1,512,863, 1,521,083 and 1,579,899.
Of these, oxonol dyes having two hydroxypyridone nuclei are decolored in development solutions containing sulfite salts and exert little adverse effect on the photographic emulsion.
However, even though dyes belonging to this family have little effect on the photographic emulsion itself, they have the disadvantage that they may spectrally sensitize spectrally sensitized emulsions in unnecessary regions and that they may cause a reduction in speed which is thought to originate in the desorption of the sensitizing dye.
Furthermore, they may remain after processing due to the increasing speed of development processing which has come into practice in recent years. It has been proposed to use dyes with a high reactivity with sulfite ions in order to solve this problem, but this approach has the disadvantages that the stability within the photographic film is not sufficient, there is a reduction in density on aging and it is not possible to obtain the desired photographic effects.
On the other hand, open chain ketomethylene couplers are used as yellow image-forming couplers, and phenol-based and naphthol-based couplers are used as the cyan image-forming couplers, for the color image-forming couplers used in color photographic materials. 5-Pyrazolone-based couplers have long been used as magenta image-forming couplers. However, recently proposals have been made for coupler structures which eliminate secondary absorption at about 430 nm for magenta dyes formed from 5-pyrazolone-based couplers, as is known from, for example, U.S. Pat. Nos. 3,369,897 and 3,725,067, JP-A-59-162548, JP-A-59-171956, JP-A-59-228252 and JP-A-60-33552 and Published International Applications (WO) 86-1915 and JP-A-61-65245. In particular, pyrazoloazole-based couplers are excellent couplers for red color reproduction and have come to be used as one component in color photographic materials in recent years.
However, despite the improvements in spectral absorption characteristics of pyrazoloazole-based couplers, they still have the disadvantage that they do not exhibit desirable color reproduction or sharpness when they are combined in oxonol dyes having the previously mentioned pyrazolone nuclei or hydroxypyridone nuclei.